1. Field of the Invention
The present invention relates to a thermal luminescence (TL) sensor system for tactical military deployment, referred herein as a Tactical Thermal Luminescence Sensor system, and abbreviated as TTLS. More particularly, the present invention identifies chemical agent warfare materials and their simulant liquids on terrestrial surfaces at a distance by recognizing the contaminant""s infrared fingerprint spectrum brought out in thermal luminescence. Most particularly, the TTLS device irradiates a suspect surface with microwave or near IR light that is absorbed into the surface and, subsequently, TL is released by the surface. An optics receiver collects the released TL radiant light and, at the most opportune irradiation time, a data acquisition system searches this TL radiant flux for the contaminant""s fingerprint infrared spectrum. A decision on the presence or absence of any-of-N contaminants is done by a neural network system that acts as a filter through real-time pattern recognition of the contaminant""s unique infrared absorption or emission spectrum.
2. Brief Description of the Related Art
In military maneuvering and industrial cleanup operations it is often vital to rapidly ascertain the presence and extent of land area chemical contamination caused by deliberate or accidental spill. Passive radiometry cannot detect liquids on a surface by infrared spectroscopy if the contaminant and its medium are in thermal equilibrium, or even in a quasi-thermal equilibrium state. An ambient thermal spectrum by the interstitial contaminant mass cannot be revealed, as it is a negligible small signal superimposed on the medium""s overall Graybody spectrum, lying well inside the noise level of standard radiometer instrumentation.
Presently, a threat liquid mass on a surface is neutralized for the safeguard of life and health with ground maps, in hand, that outline the presence of specific compounds and their surface/volume coverage. There is a need in the art for remotely detecting and identifying classes of suspect contaminants on a surface area while providing rapid and safe monitoring. The present invention addresses this and other needs.
The present invention includes an apparatus for determining chemical contamination of terrestrial landscapes and manmade surfaces from the analysis of induced thermal spectra by employing thermal luminescence. The thermal luminescence is produced using a high power beam, wherein the beam frequency is selected from the group consisting of microwave and near infrared, where the frequency lies outside the mid infrared detection bandwidth and is efficiently absorbed by the irradiated surface. The TTLS has the means for collecting these liberated thermal emissions, means for processing collected liberated thermal emissions, and means for deriving pattern recognition stages from the processed thermal emissions.
The present invention also includes a method for determining chemical contamination of terrestrial landscapes and manmade surfaces, comprising the steps of irradiating a surface with a high powered beam, collecting liberated thermal emissions, processing the collected liberated thermal emissions and deriving pattern recognition stages from the processed thermal emissions.
The standoff detection system of the present invention identifies chemical contamination on terrain from a moving platform, such as a vehicle. An intense microwave beam emitting in the W-band region irradiates a slightly wet terrestrial surface for several seconds at approximately 1.5 W cmxe2x88x921 beam intensity or less. Liberated thermal emissions are reflected, condensed, and sent to a scanning interferometer for spectral processing. The interstitial liquid mass can be identified through its infrared band structure through a simple difference-spectrum of the thermal luminescence. Measurement of the thermal luminescence is timed to occur when the surface temperature gradient peaks, giving a state of maximum emissivity contrast between the ground and the thermally excited liquid. This allows for optimum detection of an onset of the contaminant""s thermal spectrum. Generally, with the determination of a chemical contaminant, a warning, mapping or other corrective measures are taken.